Method for the preparation of calcium monohydrogen phosphate

A method for the preparation of calcium monohydrogen phosphate comprising the steps of:

• a) digesting in an aqueous medium, during a predetermined time period, a phosphate source by an acid with formation of a pulp comprising an aqueous phase containing calcium phosphate in solution and a solid phase containing impurities,
• b) separating said aqueous phase containing calcium phosphate in solution and said solid phase containing impurities, for a predetermined time period to provide a separated aqueous phase containing calcium phosphate in solution,
• c) neutralizing said separated aqueous phase containing calcium phosphate in solution at a sufficient pH to obtain a precipitation in an aqueous medium of insoluble calcium phosphate as aforementioned calcium monohydrogen phosphate, and
• d) separating said aqueous medium and said calcium monohydrogen phosphate,
• wherein step b) is carried out at a filtration rate of at least 0.1 ton of P2O5/√ΔP/m2/day, between 0.1 and 5 tons of P2O5/√ΔP/m2/day, between 0.15 and 3 tons of P2O5/√ΔP/m2/day, between 0.3 and 0.9 tons of P2O5/√ΔP/m2/day, or between 0.4 and 0.7 tons of P2O5/√ΔP/m2/day, said filtration rate being calculated according to the following equation:
• Filtration
• 
• 
• rate
• =
• Q
• P
• 
• 
• 2
• 
• O
• 
• 
• 5
• Δ
• 
• 
• P
• 
• Ω
• 
• 
• T
• f
• where
• QP205 corresponds to the quantity of P2O5 collected in the filtrate and is expressed in tons,
• Ω is the filter surface area expressed in m2,
• ΔP is the difference between the pressure at the filtrate outlet and the pressure applied to the pulp at the time of said first separation and is expressed in bar, and
• Tf is the duration of said first separation and is expressed in day.